A novel method for overcoming the strength-ductility trade-off of titanium and titanium alloys by high-density pulsed electric current

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K20408
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: Nagoya University
• Principal Investigator: Gu Shaojie 名古屋大学, 工学研究科, 特任助教 (00966830)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: マルテンサイト変態 / ヘテロ構造 / 高密度パルス電流 / 純チタンとチタン合金 / 強度と延性の向上

Outline of Final Research Achievements

This study successfully utilized high-density pulsed current treatment technology to simultaneously enhance the strength and ductility of pure titanium and titanium alloys. Generally, the mechanical properties of materials follow the natural law of the strength-ductility trade-off, meaning that improving one inevitably compromises the other. In this study, the use of high-density pulsed current treatment enabled the rapid heating and cooling of the material, forming a heterogeneous structure that includes chemical composition and microstructural inhomogeneities, thereby overcoming the strength-ductility dilemma. In the future, the method proposed in this study can be applied to other materials to enhance their mechanical properties. This is expected to contribute to sustainable material design and manufacturing, as well as the realization of a carbon-neutral society.

Free Research Field

材料力学および機械材料関連

Academic Significance and Societal Importance of the Research Achievements

本研究は、加熱速度が10^6°C/sに達する高密度パルス電流処理によって、二相α/βチタン合金材料が条状α相、残存α相、マルテンサイトα'相、及び残存β相を含む混合異質微細構造を形成することを初めて発見した。これは、従来の熱処理方法では実現が難しいものである。この混合構造は、材料の微細構造を強区と弱区に分け、それらの協働作用によって強度と延性のトレードオフを打破した。この研究成果は、高密度パルス電流処理法を用いて他の類似した二相構造材料を処理するための基礎と根拠を提供する。